Hillary Clinton delivered a blistering denunciation Thursday of Donald Trump's personal and political history with race, arguing in her most forceful terms yet that a nationalist conservative fringe had engulfed the Republican Party.

In a 31-minute address, building to a controlled simmer, Clinton did everything but call Trump a racist outright — saying he had promoted "racist lie" after "racist lie," pushed conspiracy theories with "racist undertones" and heartened racists across the country by submitting to an "emerging racist ideology known as the alt-right."

"He is taking hate groups mainstream," Clinton told supporters at a community college here, "and helping a radical fringe take over the Republican Party."

Clinton said that while a racially charged and "paranoid fringe" had always existed in politics, "it's never had the nominee of a major party stoking it, encouraging it and giving it a national megaphone, until now."

Clinton's remarks coincide with a conspicuous shift in strategy from Trump, who has spoken with more compassion about people in the country illegally and expressed a desire to win African-American support. He has even suggested he might revisit his call to deport 11 million immigrants in the United States illegally, a pivot seen as an attempt to draw in moderate voters turned off by his views.

With Trump's rise, Clinton has often struck a have-you-no-sense-of-decency theme in her critiques — warning sternly and repeatedly that the arc of his candidacy transcended standard political attack.

But her effort on Thursday was remarkable for its exhaustive accounting of Trump's controversial racial history in business and in his presidential campaign.

Clinton detailed the Justice Department's housing discrimination case against Trump during the 1970s, noting that the applications of black and Latino residents "would be marked with a 'C' — 'C' for colored."

She said state regulators had fined a Trump casino for repeatedly removing black dealers from the floor and reminded the audience of Trump's promotion of "birtherism," questioning President Barack Obama's birthplace.

She recalled his opening salvo in the Republican primary, calling Mexican immigrants rapists and criminals when he announced his candidacy, and his more recent suggestion that a judge with a Mexican heritage could not be impartial in hearing a case involving Trump University.

"This is someone who retweets white supremacists online," Clinton said, citing a posting by someone with the user name "WhiteGenocideTM. "Trump took this fringe bigot with a few dozen followers and spread his message to 11 million people."

"I'm not making this up," she warned, before digging into the site's archives: "Birth Control Makes Women Unattractive and Crazy"; "'Would You Rather Your Child Had Feminism or Cancer?'"; "Hoist It High and Proud: The Confederate Flag Proclaims a Glorious Heritage."

The address came a week after Trump hired Bannon, who has eagerly described the site as "the platform for the alt-right" — a loosely defined and contested term often associated with white nationalist and anti-immigrant sentiment.

"The de facto merger between Breitbart and the Trump campaign represents a landmark achievement for the alt-right," Clinton said.

At a rally in Manchester, N.H., on Thursday afternoon, Trump offered a pre-emptive response to Clinton's speech, portraying her attacks as directed not only at him, but also at his many supporters.

"She lies, and she smears, and she paints decent Americans — you — as racists," he said, motioning toward the crowd gathered at a hotel. "She bullies voters who only want a better future and tries to intimidate them out of voting for a change."

He offered a pointed response to Clinton and those "pushing her to spread smears and her lies about decent people."

"I have three words," he said. "I want you to remember these three words: Shame on you."

Clinton's pitch seemed aimed largely at moderate Republicans and other voters who have watched Trump's attempts in recent days to soften his image.

"Trump is trying to rebrand himself," she said. "Don't be fooled."

She detailed explicit rejections of racist behavior from prominent Republicans in the past, like Bob Dole, George W. Bush and Sen. John McCain of Arizona. And she defended the House speaker, Paul D. Ryan, and Sen. Ted Cruz, who had been attacked by Trump's campaign.

Jason Miller, a spokesman for Trump, said that with her attacks, Clinton was merely trying to direct attention away from her own controversies.

"Hillary Clinton's attempt to delete the single worst week of her political career isn't going to work," he said, citing uproars over her private email server and the Clinton Foundation.

Trump's recent efforts to moderate his tone, which have come in front of predominantly white audiences, have more than occasionally offended minority voters.

Trump has said African-Americans live in neighborhoods resembling "war zones," struggle to get by on food stamps and constantly face down errant gunfire.

"What do you have to lose?" he has asked.

On Thursday, Clinton offered her response: "The answer is everything."